These requirements cover electrically-operated clocks that form parts of a master clock system@ secondary@ cost@ pay-roll@ and other clocks intended primarily for industrial installations; and also time stamps@ job-card recorders@ timers@ and similar time-indicating and -recording appliances. These appliances are intended for use on circuits of 300 volts or less in accordance with the National Electrical Code. These requirements do not cover clocks intended primarily for household installations nor do they cover illuminated clocks designed to serve as portable electrical lamps or for other illuminating purposes.